Rifaximin Impurity 2

(2S,16Z,18E,20S,21S,22R,23R,24R,25S,26R,27S,28E)-25-(Acetyloxy)-5,21,23-trihydroxy-27-methoxy-2,4,16,20,22,24,26-heptamethyl-11-methylene-2,7-(epoxypentadeca[1,11,13]trienimino)benzofuro[4,5-e]pyrido[1,2-a]benzimidazole-1,6,15(2H,11H)-trione

(2S,16Z,18E,20S,21S,22R,23R,24R,25S,26R,27S,28E)-25-(Acetyloxy)-5,21,23-trihydroxy-27-methoxy-2,4,16,20,22,24,26-heptamethyl-11-methylene-2,7-(epoxypentadeca[1,11,13]trienimino)benzofuro[4,5-e]pyrido[1,2-a]benzimidazole-1,6,15(2H,11H)-trione